Group III-V compound semiconductors such as, for example, GaN and AlGaN, are widely used for optoelectronics, electronic devices and the like, owing to many advantages such as, for example, a wide and easily adjustable band gap energy.
In particular, light-emitting elements such as light-emitting diodes or laser diodes using group III-V or II-VI compound semiconductors may realize various colors of light such as, for example, red, green, and blue light, as well as ultraviolet light, via the development of device materials and thin-film growth technique, and may also realize white light having high luminous efficacy via the use of a fluorescent material or by combining colors. These light-emitting elements have advantages of low power consumption, a semi-permanent lifespan, fast response speed, good safety, and eco-friendly properties compared to existing light sources such as, for example, fluorescent lamps and incandescent lamps.
Accordingly, the application of light-emitting elements has been expanded to a transmission module of an optical communication apparatus, a light-emitting diode backlight, which may substitute for a cold cathode fluorescent lamp (CCFL) constituting a backlight of a liquid crystal display (LCD) apparatus, a white light-emitting diode lighting apparatus, which may substitute for a fluorescent lamp or an incandescent bulb, a vehicle headlight, and a signal lamp.
FIG. 1 is a view illustrating a conventional light-emitting element package.
In the light-emitting element package 100, a light-emitting element 130 is disposed on a substrate 110 and a lens 150 is disposed around the light-emitting element 130 to adjust the distribution of light discharged from the light-emitting element 130.
Although not illustrated, a molded part may be disposed around on the light-emitting element 130 to protect, for example, a light-emitting structure or wires. Since light is refracted when passing through the molded part, which is formed of, for example, silicon, the molded part may serve as a primary lens.
In addition, a secondary lens may be used in order to adjust the path along which light is discharged when the light-emitting element is used as a light source. The aforementioned secondary lens is commonly referred to as a “lens”.
An optical path may be greatly changed depending on the material of the lens and particularly on the shape thereof. When the lens is used to adjust the distribution of light discharged from the light-emitting element package, in particular, to increase the range of distribution, a light emission angle may be increased, but the distribution of illuminance may suffer, in particular, illuminance in a central area may be reduced.